Commit b6442eba authored by Klaus Aehlig's avatar Klaus Aehlig
Browse files

Support opportunistically allocating locks



Again, this just wraps around updateLocks, sequentially trying
to obtain all the locks mentioned.
Signed-off-by: default avatarKlaus Aehlig <aehlig@google.com>
Reviewed-by: default avatarPetr Pudlak <pudlak@google.com>
parent 6dec5ace
......@@ -39,10 +39,12 @@ module Ganeti.Locking.Waiting
, freeLocksPredicate
, downGradeLocksPredicate
, intersectLocks
, opportunisticLockUnion
) where
import Control.Arrow ((&&&), second)
import Control.Arrow ((&&&), (***), second)
import Control.Monad (liftM)
import Data.List (sort)
import qualified Data.Map as M
import Data.Maybe (fromMaybe)
import qualified Data.Set as S
......@@ -322,3 +324,24 @@ intersectLocks :: (Lock a, Ord b, Ord c)
-> b
-> LockWaiting a b c -> (LockWaiting a b c, S.Set b)
intersectLocks locks = freeLocksPredicate (not . flip elem locks)
-- | Opprotunistically allocate locks for a given owner; return the set
-- of newly actually acquired locks (i.e., locks already held before are
-- not mentioned).
opportunisticLockUnion :: (Lock a, Ord b, Ord c)
=> b
-> [(a, L.OwnerState)]
-> LockWaiting a b c
-> (LockWaiting a b c, ([a], S.Set b))
opportunisticLockUnion owner reqs state =
let locks = L.listLocks owner $ getAllocation state
reqs' = sort $ filter (uncurry (<) . (flip M.lookup locks *** Just)) reqs
maybeAllocate (s, success) (lock, ownstate) =
let (s', (result, _)) =
updateLocks owner
[(if ownstate == L.OwnShared
then L.requestShared
else L.requestExclusive) lock]
s
in (s', if result == Ok S.empty then lock:success else success)
in second (flip (,) S.empty) $ foldl maybeAllocate (state, []) reqs'
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